Plasma processing apparatus

Abstract

The present application provides a plasma processing device capable of controlling the position of a resonance point and bringing the resonance point close to the output end of a coil antenna. The device comprises an ICP antenna (21) having an input end (21I) and an output end (21O); a series circuit formed by connecting an additional inductor (24) and a variable capacitor (25) in series; and a control device (33) for changing the capacitance of the variable capacitor (25). The input end (21I) is connected to an antenna power source (23) via an antenna matching device (22), the output end (21O) is connected to the additional inductor (24), and the additional inductor (24) is connected to a ground end via the variable capacitor (25).

Description

TECHNICAL FIELD

[0001] The present application relates to a plasma processing apparatus. BACKGROUND

[0002] An etching apparatus as an example of a plasma processing apparatus has a coil antenna for generating plasma. In the coil antenna, an input terminal is connected to a high-frequency power source via a matching circuit, and an output terminal is connected to a ground terminal (for example, refer to Patent Literature 1). In this field of etching apparatuses, there is still a strong demand for changing the distribution of plasma density to a new distribution. For example, there is known a technique of changing the distribution of plasma density by providing a variable capacitor before the coil antenna and the ground terminal, and moving a resonance point by controlling the capacitance of the variable capacitor.

[0003] PRIOR ART DOCUMENTS

[0004] PATENT LITERATURE

[0005] Patent Literature 1: Japanese Patent Application Laid-Open No. 2013-157528 SUMMARY

[0006] PROBLEMS TO BE SOLVED BY THE INVENTION

[0007] In a structure in which the output terminal of the coil antenna is connected to the ground terminal via the variable capacitor, there is room for improvement in terms of obtaining a new plasma density distribution in which the resonance point is closer to the output terminal of the coil antenna, since the resonance point is limited to be closer to the output terminal of the coil antenna in principle. In addition, this case is not limited to etching apparatuses, and is also the same in other plasma processing apparatuses such as sputtering apparatuses or CVD apparatuses.

[0008] MEANS FOR SOLVING THE PROBLEMS

[0009] A plasma processing apparatus according to an embodiment has a coil antenna having an input terminal and an output terminal, a series circuit formed by connecting an additional inductor and a variable capacitor in series, and a control section that changes the capacitance of the variable capacitor, the input terminal being connected to a high-frequency power source via a matching circuit, the output terminal being connected to the additional inductor, and the additional inductor being connected to a ground terminal via the variable capacitor.

[0010] According to the above structure, the control section is able to control the position of the resonance point by changing the capacitance of the variable capacitor. Furthermore, it is possible to make the resonance point closer to the output terminal of the coil antenna, and the amount thereof is the amount in which the additional inductor is interposed between the coil antenna and the variable capacitor.

[0011] In the above-described plasma processing apparatus, it is preferable that the control section set the range of the capacitance of the variable capacitor to include a first capacitance, the first capacitance being the capacitance of the variable capacitor when a resonance point is closest to the output terminal in the range, and that the control section execute processing to make the capacitance of the variable capacitor the first capacitance when the coil antenna starts generating plasma.

[0012] Plasma generation using the coil antenna starts from the generation of capacitive plasma. Further, making the resonance point close to the output terminal of the coil antenna means bringing the peak-to-peak value in the input terminal to the highest. Therefore, by making the resonance point close to the output terminal when the coil antenna starts generating plasma, it is possible to easily generate capacitive plasma, and further, it is possible to make the start of plasma generation based on the coil antenna stable.

[0013] In the above-described plasma processing apparatus, it is preferable that, after starting the generation of the plasma, the control section use the peak-to-peak value in the input terminal to specify the capacitance of the variable capacitor for moving the resonance point from the output terminal to the input terminal.

[0014] The more the resonance point is moved from the output terminal to the input terminal, the lower the peak-to-peak value in the input terminal is. As long as the structure is to use the peak-to-peak value in the input terminal to specify the capacitance, it is possible to improve the accuracy of moving the resonance point from the output terminal to the input terminal. Plasma generation using the coil antenna starts from the generation of capacitive plasma. Making the resonance point move from the output terminal to the input terminal after the generation of capacitive plasma means lowering the peak-to-peak value in the input terminal after bringing it to the highest, and means suppressing the bias of capacitive plasma in a state where inductive plasma is induced. As a result, it is possible to make the distribution of plasma uniform in a state where inductive plasma is generated.

[0015] In the above-described plasma processing apparatus, it is preferable that the control section further use the peak-to-peak value in the output terminal in the specifying.

[0016] The more the resonance point is moved from the output terminal to the input terminal, the higher the peak-to-peak value in the output terminal is. As long as the structure is to use the peak-to-peak value in the input terminal and the peak-to-peak value in the output terminal to specify the capacitance, it is possible to set the destination of the movement of the resonance point based on the specified capacitance with higher accuracy.

[0017] In the above-described plasma processing apparatus, it is preferable that the plasma processing apparatus further include a capacitively coupled antenna connected to the coil antenna, that the range of the capacitance of the variable capacitor set by the control section include a first specific capacitance and a second specific capacitance, that the first specific capacitance be the capacitance of the variable capacitor when a resonance point is closest to a connection point of the coil antenna and the capacitively coupled antenna in the range, that the second specific capacitance be a capacitance of the variable capacitor different from the first specific capacitance, and that the control section execute: a process of setting the capacitance of the variable capacitor to the first specific capacitance; and a process of setting the capacitance of the variable capacitor to the second specific capacitance.

[0018] The peak-to-peak value in the capacitively coupled antenna is relatively low when the resonance point is at the connection point of the coil antenna and the capacitively coupled antenna, and, on the contrary, the peak-to-peak value in the capacitively coupled antenna is relatively increased the farther the resonance point is from the connection point of the coil antenna and the capacitively coupled antenna. If the capacitance of the variable capacitor is set to the first specific capacitance and the second specific capacitance, respectively, a state in which the peak-to-peak value in the capacitively coupled antenna is relatively reduced and a state in which the peak-to-peak value in the capacitively coupled antenna is relatively increased are realized, respectively. Thus, it is possible to switch the function of the capacitively coupled antenna, such as removal and stop of the deposit based on the capacitively coupled antenna. BRIEF DESCRIPTION OF DRAWINGS

[0019] Fig. 1 is a schematic view showing a device structure of an etching device.

[0020] Fig. 2 is a schematic view showing a circuit structure in an etching device and a structure of a control device.

[0021] Fig. 3 is a chart showing a peak-to-peak value in an ICP antenna and an additional inductor. DETAILED DESCRIPTION

[0022] Hereinafter, referring to Figs. 1-3 An embodiment of a plasma processing apparatus will be described.

[0023] As shown in Fig. 1 An etching device 10, which is an example of a plasma processing apparatus, includes a chamber body 11 having a bottomed cylindrical shape, and a dielectric window 12 sealing an upper side opening of the chamber body 11. The chamber body 11 and the dielectric window 12 define a chamber space 11S.

[0024] The chamber body 11 is a metal structure body of aluminum or the like. The dielectric window 12 includes a base 12A made of quartz, and a cover portion 12B which is a resin film made of a resin such as polyimide. The cover portion 12B covers a surface of the base 12A on the chamber space 11S side.

[0025] A stage 13 is housed in the chamber space 11S. The stage 13 holds a substrate S that is an object of etching. A bias electrode 13P built in the stage 13 is connected with a bias power source 15 via a bias matcher 14. The bias power source 15 outputs high-frequency electric power of 13.56 MHz. The bias matcher 14 suppresses reflected waves caused by a load by matching an output impedance of the bias power source 15 and an input impedance of the load to which the high-frequency electric power is input.

[0026] An ICP (Inductively-Coupled Plasma) antenna 21, which is an example of a coil antenna, is disposed on a side opposite to the chamber space 11S with respect to the dielectric window 12. The ICP antenna 21 is constituted of, for example, a two-stage coil having a spiral shape in which two turns are wound in a circumferential direction of the substrate S on each stage. The ICP antenna 21 has a predetermined inductance. For example, the inductance of the ICP antenna 21 is preferably 0.3 μH or more and 4.0 μH or less.

[0027] The ICP antenna 21 has an input end 21I and an output end 21O. The input end 21I is an end portion of the coil of the lower stage among the two-stage coil constituting the ICP antenna 21, and is an end portion on an outer side in the spiral shape. The output end 21O is an end portion of the coil of the upper stage among the two-stage coil constituting the ICP antenna 21, and is an end portion on a center side in the spiral shape.

[0028] The input end 21I of the ICP antenna 21 is connected with an antenna power source 23 via an antenna matcher 22. The antenna power source 23 is an example of a high-frequency power source, and outputs, for example, high-frequency electric power of 13.56 MHz. The antenna matcher 22 is an example of a matching circuit. The antenna matcher 22 suppresses reflected waves caused by a load by matching an output impedance of the antenna power source 23 and an input impedance of the load to which the high-frequency electric power from the antenna power source 23 is input.

[0029] The output end 21O of the ICP antenna 21 is connected with an additional inductor 24 via a node N1. The additional inductor 24 is connected with a ground via a variable capacitor 25. That is, the additional inductor 24 and the variable capacitor 25 constitute a series circuit that connects the output end 21O of the ICP antenna 21 to the ground.

[0030] The variable capacitor 25 can take a range of capacitances C, for example, from 10 pF to 1000 pF. The inductance L of the additional inductor 24 is set to an arbitrary value that satisfies ωL-1 / ωC=0 (ω is an angular frequency) for the capacitance C that the variable capacitor 25 can take, for example. As an example, the inductance L of the additional inductor 24 is set to a value at which the resonance point RP is located at the output terminal 21O of the ICP antenna 21 (refer to FIG. 2) by numerical calculation using the maximum value in the range of the capacitance C that the variable capacitor 25 can take. The inductance L of the additional inductor 24 is preferably 0.3 μH or more and 2.0 μH or less, for example. Fig. 3

[0031] The resonance point RP moves inside the ICP antenna 21 by changing the capacitance C of the variable capacitor 25. Thus, the peak-to-peak value, i.e., Vpp, at each position inside the ICP antenna 21 including the input terminal 21I and the output terminal 21O changes. The Vpp is the difference between the maximum value and the minimum value of the voltage at each position in the high-frequency circuit (the circuit from the high-frequency power source 23 to the variable capacitor 25) and can also be referred to as the peak-to-peak voltage detected at each position. Fig. 2

[0032] The capacitive coupling antenna 26 is arranged between the dielectric window 12 and the ICP antenna 21. The capacitive coupling antenna 26 is an electrode that extends radially above the dielectric window 12 in parallel with the dielectric window 12. When a voltage is applied to the capacitive coupling antenna 26 in a state in which the plasma P is generated in the chamber space 11S, ions are introduced to the inner surface of the dielectric window 12. Thus, the deposits adhering to the inner surface of the dielectric window 12 are removed.

[0033] The additional inductor 24 and the capacitive coupling antenna 26 are connected in parallel to the output terminal 21O of the ICP antenna 21 via the node N1. That is, the node N1 is a connection point of the ICP antenna 21 and the capacitive coupling antenna 26. In addition, the node N1 is substantially equal in electrical potential to the output terminal 21O on the transmission path of the high-frequency power.

[0034] The chamber main body 11 is provided with an exhaust port 11P. The exhaust port 11P is connected to an exhaust unit 31 that exhausts the fluid in the chamber space 11S. The exhaust unit 31 is constituted by a pressure adjusting valve that adjusts the pressure in the chamber space 11S and various pumps, for example.

[0035] The dielectric window 12 is provided with a gas supply port 12P. The gas supply port 12P is connected to a gas supply unit 32 that flows the etching gas into the chamber space 11S. The gas supply unit 32 is a mass flow controller that supplies sulfur hexafluoride gas as an example of a fluorine-containing gas or boron trifluoride as an example of a boron-containing gas, for example.

[0036] ​​The etching apparatus 10 is provided with a control device 33. The control device 33 controls each part of the etching apparatus 10, and executes various processes for generating plasma P in the chamber space 11S.

[0037] As shown in FIG. 2, the antenna matching device 22 is composed of two variable capacitors 22A, 22B and two fixed capacitors 22C, 22D, for example. The two variable capacitors 22A, 22B are connected in parallel to the antenna power source 23 via a node N2. One terminal of the variable capacitor 22A is connected to the antenna power source 23 via the node N2, and the other terminal is connected to a ground terminal. One terminal of the variable capacitor 22B is connected to the antenna power source 23 via the node N2, and the other terminal is connected to the input terminal 21I of the ICP antenna 21 via a parallel circuit composed of the two fixed capacitors 22C, 22D. Fig. 2 [Control Device]

[0038] The control device 33 is provided with a control section 33A, a storage section 33B, and a detection section 33C. The control section 33A controls the driving of each part of the etching apparatus 10. The storage section 33B stores programs and processing conditions for controlling the driving of each part of the etching apparatus 10. The detection section 33C detects an input Vpp as Vpp in the input terminal 21I and an output Vpp as Vpp in the output terminal 21O.

[0039] In an example, the storage section 33B stores a first target value, a second target value, a third target value, and a fourth target value as processing conditions. The first target value is a capacitance C of the variable capacitor 25 used at the time of starting generation of the plasma P. The first target value is an example of a first capacitance. The first capacitance is a value of the capacitance C at the time of obtaining a resonance point RP closest to the output terminal 21O among resonance points RP moved by changing the capacitance C.

[0040] The first target value can be obtained, for example, by a test of starting generation of the plasma P using the ICP antenna 21. In this test, generation of the plasma P using the ICP antenna 21 is performed in each of a plurality of capacitances C while one of the plurality of capacitances C is sequentially changed and set to the variable capacitor 25. Also, the capacitance C at which the input Vpp is largest among the plurality of capacitances C used can be set as the first target value.

[0041] Alternatively, the first target value can be obtained by numerical calculation of the range of the capacitance C available for the variable capacitor 25 and the inductance L of the additional inductor 24. For example, in the numerical calculation, the capacitance C in the range of the capacitance C available for the variable capacitor 25, which is calculated to be the capacitance C at which the output Vpp becomes the smallest, can be set as the first target value.

[0042] Alternatively, the first target value can be obtained by numerical calculation of the range of the capacitance C available for the variable capacitor 25 and the inductance L of the additional inductor 24. For example, in the numerical calculation, the capacitance C in the range of the capacitance C available for the variable capacitor 25, which is calculated to be the capacitance C at which the output Vpp becomes the smallest, can be set as the first target value.

[0043] The second target value is a value of the input Vpp and the output Vpp used after the start of the generation of the plasma P. The capacitance C at the time when the input Vpp and the output Vpp are the second target value is an example of the second capacitance. The second capacitance is a value different from the first capacitance, and is, for example, a value of the capacitance C at the time when the input Vpp and the output Vpp are approximately equal.

[0044] The second target value can also be obtained, for example, by a test in which the plasma P using the ICP antenna 21 is continuously generated. In this test, the variable capacitor 25 is set while one of a plurality of capacitances C is sequentially changed, and the generation of the plasma P using the ICP antenna 21 is performed in each of the capacitances C. Also, the input Vpp and the output Vpp at the time when the input Vpp and the output Vpp are approximately equal among the plurality of capacitances C used can be set as the second target value.

[0045] Alternatively, the second target value can also be obtained by numerical calculation of the inductance of the ICP antenna 21, the inductance L of the additional inductor 24, and the capacitance C of the variable capacitor 25. In this numerical calculation, the input Vpp and the output Vpp at the time when the input Vpp and the output Vpp are approximately equal after the start of the generation among the range of the capacitance C available for the variable capacitor 25 can be set as the second target value.

[0046] The third target value is a value of the input Vpp and the output Vpp used when the removal of the deposit attached to the inner surface of the dielectric window 12 by the capacitively coupled antenna 26 is stopped. The capacitance C at the time when the input Vpp and the output Vpp are the third target value is an example of the first specific capacitance. The first specific capacitance is, for example, a value of the capacitance C at the time when the resonance point RP is located at the most proximal node N1. Also, in the present embodiment, the output Vpp is approximately equal to the Vpp at the node N1 electrically, and thus the output Vpp coincides with the Vpp at the node N1. Therefore, the first specific capacitance coincides with the first capacitance.

[0047] The third target value can also be obtained by numerical calculation of the inductance L of the additional inductor 24 and the range of the capacitance C available for the variable capacitor 25. For example, in this numerical calculation, the value of the capacitance C at which the Vpp at the node N1 becomes the smallest among the range of the capacitance C available for the variable capacitor 25 is calculated. Also, the input Vpp and the output Vpp when the calculated capacitance C is applied can be set as the third target value.

[0048] The fourth target value is a value of the input Vpp and the output Vpp used when the deposit attached to the inner surface of the dielectric window 12 is removed by the capacitively coupled antenna 26. The fourth target value is a value different from the third target value. The capacitance C at the time when the input Vpp and the output Vpp are the fourth target value is an example of the second specific capacitance. The second specific capacitance is a value of the capacitance C different from the first specific capacitance.

[0049] As an example, the same value as the second target value is used as the fourth target value. At this time, the second specific capacitance coincides with the second capacitance. In addition, the fourth target value can be a value different from the second target value as long as it is a value different from the third target value.

[0050] The fourth target value can be obtained, for example, by a test in which the plasma P is continuously generated using the ICP antenna 21. In this test, the generation of the plasma P using the ICP antenna 21 is performed in each of the capacitances C while the capacitance C is sequentially changed by the variable capacitor 25. Also, in the plurality of capacitances C used, the input Vpp and the output Vpp at the time when the output Vpp is a size at which the accumulated material can be removed by the capacitive coupling antenna 26 can be set as the fourth target value.

[0051] [Effects of Embodiments]

[0052] Hereinafter, the effects of the etching apparatus 10 will be described with reference to the drawings. Fig. 3 The effects of the etching apparatus 10 will be described. Fig. 3 The graph 40 shown in FIG. 4 schematically shows the Vpp at each position of the ICP antenna 21 and the additional inductor 24 at the time when the generation of the plasma P is started and after the start. In addition, in the graph 40, the horizontal axis indicates the time, and the vertical axis indicates the Vpp. Fig. 3 In the horizontal axis of the graph 40 shown in FIG. 4, the left end indicates the input terminal 21I, the position of the broken line 41 indicates the output terminal 21O and the node N1, and the position of the broken line 42 indicates the connection point of the additional inductor 24 and the variable capacitor 25.

[0053] First, the control section 33A controls the exhaust section 31, and thereby the chamber space 11S is exhausted until it becomes a predetermined pressure. Next, the control section 33A controls the gas supply section 32, and thereby the etching gas is supplied to the chamber space 11S. Further, the control section 33A sets the capacitance C of the variable capacitor 25 to the first capacitance with reference to the first target value stored in the storage section 33B. Also, the control section 33A controls the antenna power supply 23 to supply the high-frequency electric power to the ICP antenna 21. Thus, the capacitive plasma, which is an example of the plasma P, is started to be generated in the chamber space 11S.

[0054] As described above, the etching apparatus 10 according to the embodiment can set the capacitance C of the variable capacitor 25 to the first capacitance, the second capacitance, or the third capacitance. Fig. 3As shown, at the start of the generation of the plasma P, the control section 33A sets the capacitance C of the variable capacitor 25 to the first capacitance, thereby causing the resonance point RP to be located at a position closest to the output terminal 21O. The input Vpp becomes the maximum when the resonance point RP is closest to the output terminal 21O of the ICP antenna 21. As a result, by causing the resonance point RP to be close to the output terminal 21O at the start of the generation of the plasma P by the ICP antenna 21, it is possible to easily generate the capacitive plasma in the vicinity of the input terminal 21I. Also, it is possible to stabilize the start of the generation of the plasma P by the ICP antenna 21.

[0055] Suppose, in the case of a structure that does not include the additional inductor 24, even if it is desired to cause the resonance point RP to be close to the output terminal 21O, the resonance point RP shifts from the output terminal 21O toward the input terminal 21I by an amount that is the amount of the reactance (1 / ωC) of the variable capacitor 25. In contrast to this, when the additional inductor 24 is provided between the ICP antenna 21 and the variable capacitor 25, the resultant reactance of the additional inductor 24 and the variable capacitor 25 is expressed as ωL-1 / ωC. Also, by setting the inductance L of the additional inductor 24 and the capacitance C of the variable capacitor 25 in a manner that satisfies ωL-1 / ωC = 0, it is possible to cause the resonance point RP to be closer to the output terminal 21O.

[0056] In addition, since the output terminal 21O and the node N1 are electrically substantially equal, at the start of the generation of the plasma P, it becomes a state in which the resonance point RP is located at the node N1. In other words, at the start of the generation of the plasma P, the capacitance C set by the control section 33A is the first capacitance, and is also the first specified capacitance. When the resonance point RP is located at the node N1, it is a state in which Vpp at the node N1, that is, Vpp of the capacitive coupling antenna 26, is the minimum, and thus the generation of the capacitive plasma by the capacitive coupling antenna 26 is suppressed. Therefore, at the start of the generation of the plasma P, the removal of the deposits adhering to the inner surface of the dielectric window 12 by the capacitive coupling antenna 26 is stopped.

[0057] Next, after the start of the generation of the plasma P, the control section 33A sets the capacitance C of the variable capacitor 25 to the second capacitance with reference to the second target value stored in the storage section 33B and the measured values of the input Vpp and the output Vpp detected by the detection section 33C.

[0058] In one example, the control section 33A specifies the second capacitance in a manner that the input Vpp and the measured value of the output Vpp detected by the detection section 33C approach the second target value, using the control data. The control data is, for example, a relational expression or a table that relates the difference between the second target value and the measured value and the capacitance C in a manner that the measured value of the detection section 33C approaches the second target value. The output Vpp increases and the input Vpp decreases as the resonance point RP moves from the output terminal 210 toward the input terminal 211, and thus a relational expression or a table that represents such a relationship can be used as the control data. The control data is stored in the storage section 33B.

[0059] After starting the generation of the plasma P, the control section 33A sets the capacitance C of the variable capacitor 25 to the second capacitance specified from the second target value and the measured values of the input Vpp and the output Vpp. The control section 33A sets the capacitance C to the second capacitance, thereby moving the resonance point RP from the output terminal 210 to between the input terminal 211 and the output terminal 210 in a manner that the input Vpp and the output Vpp become substantially equal.

[0060] During the generation of the plasma P, after initially generating a capacitive plasma, an inductive plasma that is one example of the plasma P is induced from the capacitive plasma. Moving the resonance point RP away from the output terminal 210 after generating the capacitive plasma means that the input Vpp is raised to the highest and then lowered, and the bias of the capacitive plasma is suppressed in a state in which the inductive plasma is induced. As a result, after starting the generation of the plasma P, the distribution of the plasma P becomes a uniform state in a state in which the inductive plasma is generated.

[0061] In addition, in the present embodiment, the capacitance C set by the control section 33A after starting the generation of the plasma P is the second capacitance, and is also the second specified capacitance. By moving the resonance point RP from the output terminal 210 to between the input terminal 211 and the output terminal 210, a state in which the Vpp at the node N1, that is, the Vpp of the capacitive coupling antenna 26, is increased compared to when the resonance point RP is located at the output terminal 210 is achieved. As a result, after starting the generation of the plasma P, the capacitive plasma generation based on the capacitive coupling antenna 26 is performed. Thereby, the deposits attached to the inner surface of the dielectric window 12 are removed by the capacitive coupling antenna 26, and the attachment of new deposits to the inner surface of the dielectric window 12 is suppressed.

[0062] As one example, the generation of the plasma P is performed using the following etching conditions with respect to the etching device 10. In addition, the etching conditions are not limited to the following conditions.

[0063] [Etching Conditions]

[0064] • Substrate: Sapphire substrate

[0065] • High-frequency power for antenna: 2100 W

[0066] • High-frequency power for bias: 1000 W

[0067] • Frequency of high-frequency power for bias: 2 MHz

[0068] • Etching gas: BCl3

[0069] • Flow rate of etching gas: 150 seem

[0070] [Effects of Embodiments]

[0071] According to the above-described embodiments, the following enumerated effects can be obtained.

[0072] (1) The control section 33A changes the capacitance C of the variable capacitor 25, and thereby can control the position of the resonance point RP. Also, the resonance point RP can be made to approach the output terminal 21O of the ICP antenna 21 by the amount that the additional inductor 24 is interposed between the ICP antenna 21 and the variable capacitor 25.

[0073] (2) When the ICP antenna 21 starts generating the plasma P, the capacitance C of the variable capacitor 25 is set to the 1st capacitance, and thereby the resonance point RP is located at the position closest to the output terminal 21O. Thereby, the state is made in which the input Vpp is raised to the highest. Therefore, the capacitive plasma can be easily generated, and further the start of the generation of the plasma P based on the ICP antenna 21 can be made stable.

[0074] (3) After the start of the generation of the plasma P, the capacitance C of the variable capacitor 25 is set to the 2nd capacitance in such a manner that the input Vpp and the output Vpp approach the 2nd target value, and thereby the resonance point RP is moved from the output terminal 21O to between the input terminal 21I and the output terminal 21O. Thereby, the state is made in which the input Vpp and the output Vpp are approximately equal. As a result, since the bias of the plasma P based on the capacitive plasma is suppressed, the distribution of the plasma P after the start of the generation of the plasma P can be made uniform.

[0075] (4) When the control section 33A specifies the 2nd capacitance, the measurement values of the input Vpp and the output Vpp detected by the detection section 33C are used, and thereby the accuracy of moving the resonance point RP from the output terminal 21O toward the input terminal 21I can be improved.

[0076] (5) When the plasma P is started to be generated, the capacitance C of the variable capacitor 25 is set to the first specific capacitance, and thus the removal of the deposits based on the capacitive coupling antenna 26 is stopped. On the other hand, after the plasma P is started to be generated, the capacitance C of the variable capacitor 25 is set to the second specific capacitance, and thus the deposits are removed by the capacitive coupling antenna 26. That is, by setting the capacitance C of the variable capacitor 25 to the first specific capacitance and the second specific capacitance, respectively, a state in which the Vpp in the capacitive coupling antenna 26 is relatively reduced and a state in which the Vpp in the capacitive coupling antenna 26 is relatively increased are realized, respectively. Thus, the function of the capacitive coupling antenna 26 can be switched, such as the removal and stop of the deposits based on the capacitive coupling antenna 26.

[0077] Further, the above embodiment can be appropriately changed and implemented as described below.

[0078] • The structure in which the capacitive coupling antenna 26 is connected to the output terminal 21O of the ICP antenna 21 via the node N1 is exemplified. However, it is not limited thereto, and for example, an electrode can be provided at an arbitrary position between the input terminal 21I and the output terminal 21O of the ICP antenna 21, and the capacitive coupling antenna 26 is connected to the electrode.

[0079] As a specific example, a terminal is provided at the position of the resonance point RP when the input Vpp and the output Vpp are the second target values, and the capacitive coupling antenna 26 is connected to the terminal. At this time, after the plasma P is started to be generated, the capacitance C set by the control section 33A is the second capacitance, and is also the first specific capacitance. Therefore, after the plasma P is started to be generated, since the Vpp of the capacitive coupling antenna 26 is in a state in which it is the smallest, the capacitive plasma generation based on the capacitive coupling antenna 26 is suppressed.

[0080] Further, after the plasma P is started to be generated, the control section 33A sets the capacitance C to the second capacitance, that is, from the first specific capacitance to the second specific capacitance, and thus the resonance point RP is moved from the connection point of the ICP antenna 21 and the capacitive coupling antenna 26. The second specific capacitance at this time is an arbitrary capacitance different from the second capacitance, and for example, it can be the first capacitance. Thus, the Vpp at the connection point is increased. As a result, the capacitive plasma generation based on the capacitive coupling antenna 26 is performed. As described above, even in the structure in which the capacitive coupling antenna 26 is connected to the position of the resonance point RP when the input Vpp and the output Vpp are the second target values, the function of the capacitive coupling antenna 26 can be switched.

[0081] • The structure in which the etching device 10 is provided with the capacitive coupling antenna 26 is exemplified. However, it is not limited thereto, and for example, as long as it is a structure in which the deposits of the inner surface of the ceiling and the like can be removed by other means, the etching device 10 can not be provided with the capacitive coupling antenna 26.

[0082] • The configuration in which the control section 33A specifies the second capacitance using the measured values of the input Vpp and the output Vpp after starting the generation of the plasma P is exemplified. However, it is not limited thereto, and for example, it can be a configuration in which the measured value of the input Vpp is only referred to for specifying the second capacitance. At this time, instead of the measured value of the output Vpp, for example, the output Vpp calculated from the inductance L of the additional inductor 24 and the first capacitance set to the variable capacitor 25 at the time of starting the generation of the plasma P can be used.

[0083] As long as the control section 33A specifies the second capacitance using the measured values of the input Vpp and the output Vpp, compared to the configuration in which the measured value of the input Vpp is only referred to for specifying the second capacitance, the moving destination of the resonance point RP based on the specified second capacitance can be set with higher accuracy. In contrast, as long as it is the configuration in which the measured value of the input Vpp is only referred to for specifying the second capacitance, the detection section 33C does not need to detect the output Vpp, and the calculation processing of specifying the second capacitance can be simplified.

[0084] • The configuration in which the control section 33A specifies the second capacitance using the measured values of the input Vpp and the output Vpp is exemplified. Instead of this, for example, the second capacitance obtained in advance can be calculated using the values of the inductance of the ICP antenna 21, the inductance L of the additional inductor 24, and the capacitance C of the variable capacitor 25. At this time, the detection section 33C does not need to detect the input Vpp and the output Vpp, and the calculation processing of specifying the second capacitance can be simplified.

[0085] • The coil constituting the ICP antenna 21 can be one segment, or three or more segments, for example.

[0086] • As for the plasma processing device, it is not limited to the etching device 10, and for example, it can be a film forming device that generates a deposit from a film forming gas, or a surface processing device that irradiates a plasma to the surface of an object.

[0087] Explanation of Reference Numerals

[0088] N1, N2... Node

[0089] P... Plasma

[0090] RP... Resonance Point

[0091] 10... Etching Device

[0092] 21... ICP Antenna

[0093] 21I... Input Terminal

[0094] 21O... Output Terminal

[0095] 22 … antenna matching device

[0096] 23 … antenna power supply

[0097] 24 … additional inductor

[0098] 25 … variable capacitor

[0099] 26 … capacitively coupled antenna

[0100] 33 … control device

[0101] 33A … control section

[0102] 33B … storage section

[0103] 33C … detection section

Claims

1. A plasma processing apparatus comprising: a coil antenna having an input terminal and an output terminal; a capacitively coupled antenna connected to the coil antenna; a series circuit formed by connecting an additional inductor and a variable capacitor in series; and a control section that changes a capacitance of the variable capacitor, the input terminal is connected to a high-frequency power source via a matching circuit, the output terminal is connected to the additional inductor, the additional inductor is connected to a ground terminal via the variable capacitor, a range of the capacitance of the variable capacitor set by the control section includes a first specific capacitance and a second specific capacitance, the first specific capacitance is the capacitance of the variable capacitor when a resonance point is closest to a connection point of the coil antenna and the capacitively coupled antenna in the range, after the coil antenna starts generating the plasma, the control section specifies the capacitance of the variable capacitor for moving the resonance point from the output terminal to the input terminal using a peak-to-peak value in the input terminal and a peak-to-peak value in the output terminal, and the second specific capacitance is the capacitance when the peak-to-peak value in the input terminal and the peak-to-peak value in the output terminal are equal.

2. The plasma processing apparatus according to claim 1, wherein the range of the capacitance of the variable capacitor set by the control section includes a first capacitance, the first capacitance is the capacitance of the variable capacitor when a resonance point is closest to the output terminal in the range, and the control section performs a process of making the capacitance of the variable capacitor the first capacitance when the coil antenna starts generating the plasma.

3. The plasma processing apparatus according to claim 1, wherein the control section performs a process of setting the capacitance of the variable capacitor to the first specific capacitance and a process of setting the capacitance of the variable capacitor to the second specific capacitance, respectively. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

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